Genetic and biochemical experiments have suggested that DNA-dependent RNA polymerase may play a direct role in regulating transciption during the differentiation of Bacillus subtilis into spores. We propose to further investigate this possibility by examining the subunit composition and transcriptional specificity of RNA polymerase from vegetative and sporulating bacteria. (a) A newly identified subunit of RNA polymerase from vegetative cells termed delta directs accurate transcription of a class of phage genes. The possible role of the delta protein in accurate transcription of vegetative genes of B. subtilis DNA will be investigated. (b) An early event in the sporulation process is the inhibition of the sigma subunit of RNA polymerase. We will attempt to isolate a component from sporulating cells that interferes with the function of sigma. (c) We propose to isolate a form of RNA polymerase from sporulating cells that lacks sigma factor and that preferentially copies RNA from the heavy DNA strand fraction of native B. subtilis DNA. (d) A series of long-lived RNAs from sporulating cells has been isolated by electrophoresis on polyacrylamide slab gels. In vitro translation experiments will be used to determine whether these RNAs are messengers for a class of sporulation proteins that are apparently translated from relatively stable messengers in vivo. (e) We propose to use these RNAs as probes for identifiying endonuclease restriction fragments of B. subtilis DNA carrying sporulation genes.